Airport staff could face prosecution if they have anything to do with US flights which allegedly take terror suspects to be tortured, it is claimed.

Scottish human rights and legal experts said airport employees could be accused of aiding and abetting a crime.

There have been claims that CIA planes have refuelled at Prestwick and Glasgow airports while transferring suspects.

The US has confirmed that transfer or "rendition" flights have taken place but said it does not conduct torture.

A number of former detainees have alleged that they were taken on "ghost flights" and tortured in secret CIA prisons around the world.

US Secretary of State Condoleezza Rice has refused to comment on claims of secret prisons used for torture.

'Blind eye'

Scottish airports were among a number across Europe which were said to have been used for the flights.

Governments round the world have been pressing for more information about the flights, their passengers and their destinations.

Human rights groups have already called for the flights to be stopped, while MPs have asked the UK Government to provide more information.

People who knowingly assist other people to commit a criminal offence expose themselves to the risk of prosecution

Professor Chris GaneAberdeen University

One of Scotland's leading academic lawyers, Professor Chris Gane of Aberdeen University, warned individual airport staff who helped to process or service any such flights could face prosecution.

Aiding and abetting torture is illegal in domestic, as well as in international, law.

Speaking to BBC Radio Scotland, Prof Gane said: "People who knowingly assist other people to commit a criminal offence expose themselves to the risk of prosecution for those criminal offences.

"That would mean, for example, an employee at a UK airport who is instructed to or who is encouraged to assist in these flights - if these flights really are taking place - then that person raises the real risk of being exposed to prosecution for that assistance.

"If they genuinely had no real knowledge of what is going on, then that would be a defence to a criminal charge.

"But if they knew what was going on or if they knowingly turned a blind eye and carried on and assisted, there is the prospect of a criminal offence having been committed."

Human rights groups echoed Prof Gane's views, adding that airport employees faced at least a theoretical chance of having to account in the courts for what they knew, and what they did.

Condoleezza Rice has defended the US policy of "rendition"

John Scott, of the Scottish Human Rights Centre, said staff should refuse to help refuel or process suspect flights.

He said: "I think they [airport staff] have to be exceptionally careful because of the information they now have.

"It is the case that staff are now on notice and if they were to contribute in facilitating these flights, it is possible that they could be subject to prosecution themselves.

"The next time they deal with one of these flights, I think they should really be asking questions and if they don't get answers they should be refusing to help in any way."

Scottish Green MSP Chris Ballance and Rosemary Burnett, director of the Scottish section of Amnesty International, have led a delegation to the US Consulate in Edinburgh calling for the flights to be stopped.

Mr Ballance said: "From the individual statements of those who have been abducted to the highest level of legal expertise, it seems clear to me that the US is committing a crime.

"Even if those transported on the CIA flights were not being taken to secret places of detention to be interrogated under torture, the practice of rendition - the practice of turning people over to the custody of another country without legal process - is entirely illegal."

On Wednesday during Prime Minister's Questions, Tony Blair defended co-operation with the US over the secret transfer of terrorism suspects .